1. Field of the Invention
This invention relates to a collapsible vertical wind mill and, more particularly, to a highly safe vertically collapsible wind mill, which has a self-starting function, a capability of withstanding strong winds and a capability of self-adjusting the revolving rate according to the exerted wind pressure through automatic deformation of a main wing assembly according to the momentum thereof.
2. Description of the Prior Art
Winds on earth are one of the most readily utilizable types of natural energy to the mankind.
The wind, therefore, had been used in practice in various forms before the development of the modern industries.
However, the utilization of wind mills which convert winds into energy had been on the decline with the utilization of electric and steam energy based on coal, petroleum, gas, etc. and also the development of various internal combustion engines. At present, wind mills can be seen, which are mostly present for the purpose of sightseeing rather than for practical purposes.
In the recent insufficient energy circumstances, various energy sources are reconsidered, and there is deep interest again on the utility of wind forces as part of the overall energy resources.
As an example, there has been proposed a method of increasing the speed of air stream to obtain output in excess of a predetermined amount and driving a turbine by utilizing the increased speed air stream thus obtained (as disclosed in Japanese Patent Disclosure 51-41150). In this method, however, turbine blade portion is comparatively complicated and the maintenance thereof is not so easy.
Also, there is a wind mill of vertical type, which has a feature that the dimension of the wind mill can be reduced for the same output (as disclosed in Japanese Patent Publication 53-44972). This structure, however has too many movable components, and its improvement is desired from the consideration of the installation and maintenance in mountain areas.
As for the structure of the wind mill, various types have been proposed, including horizontal shaft types such as propeller type and turbine type, a Robinson cup type, a rotor application type and Robinson cup application type. These types of the structure have own merits and demerits. Inconvenience that is found in these cases is that it is necessary to match the rotor in a particular direction with respect to the direction of wind and that it is necessary to provide acceleration to the rotor in an initial stage of operation.
More specifically, in a conventional Darrieus type wind mill (including straight wing type), it is difficult to obtain the start without use of any other forces than wind force, and it is necessary to combine this wind mill with a Savonius wind mill or incorporate an electric motor.
Further, spoiler or braking means such as an electromagnetic brake or manual brake that require additional expenditure are necessary to suppress excessive rotation of the wind mill when prevailing winds are strong (e.g., with air speed of 15 m/sec. or above).